This post is a little late but as you have most likely noticed from the video on the home page, the car has completely transformed and is up and running. The use of the double garage proved very helpful and we were both working hard on many components of the car. We started by completely rebuilding the battery boxes and the mounting method. Once we got the idea, it was simple to create the other boxes. 

We wanted to work as much as possible because we had a very tight deadline. EV fest was only a couple months away and we were dedicated to ensuring the car was capable of being driven by that date. Sure enough, it was, but the road to success was rough, we blew up a controller during the testing process and had to pain stakingly trouble shoot the issues. Proudly, we completed the car and were so excited, we couldn't wait to take it for a spin however, because we took it apart with the idea of creating a race day car, we couldn't road test it. 

We are currently reconfiguring the throttle and controller for improved power deliver and adding the necessary safety components required to pass safety. Once complete, we will be able to drive the car to our shows without the use of the car trailer.  We hope to have this complete within the next couple months.

Hello followers - it's been a long time.

The 944 has finally been taken out of it's winter storage and has been brought to the new Singular Motion headquarters in Newmarket. We now have a roomy 2-car workshop where we can finally make some progress on this conversion. The cobwebs have been swept away, and we have started re-testing the systems that were previously completed.

One interesting thing we found was that our battery voltage has slowly climbed.... I really don't understand how this is possible, considering that all batteries have a small leakage current which should eventually drain the battery. The only explanation that I can think of is that the chemistry hadn't settled the last time we were charging, and since we charged as full as we could, this brought the voltage even higher as the chemistry gelled. Each cell is now resting at about 4.7V which is quite a bit higher than the maximum recommended voltage set out by the manufacturer. I will have to set up our heating element and try to discharge the pack down to a better level. These batteries certainly do have some unusual behaviour.

The next step is to build some sealed battery boxes and a new frame to hold them into the car. Because of the motor adapter we bought, the secondary shaft of the motor is interfering with the battery locations. This means that the bottom row of batteries will have to be installed from underneath the car, and the top row will have be lowered in from the top. The motor shaft will then be sitting between the two rows.

With the new workshop I'm sure we'll be rolling in no time.

Happy New Year fellow EVers,

Things have been slow and cold lately in Toronto. Cold being the key word there. Without heated facilities, we haven't spent much time with the 944. I just bought a small heater, and insulated coveralls, so perhaps I can get some work done in the near future.

We're currently working on making the BMS system operate remotely from the batteries. Our BMS design currently uses a resistive bypass circuit on each cell that can be switched on during charging to prevent overcharge. This design is inherently inefficient, and produces a lot of heat. Because of the limited spacing of our battery cells, we were worried that the hot resistors were too close to the adjacent batteries, when the BMS was mounted directly on the cells. We are going to remotely mount the BMS inside the cabin of the car, where we can more easily monitor the cell voltages, as well as properly mediate the heat produced while charging.

We completed the wiring with all of the terminals including a plug between BMS and battery in case the batteries need to be removed/replaced. When the first battery was plugged in, we had a malfunction in the BMS. We tried a second BMS board, and it didn't work either.... Needless to say, I'll be spending some time re-testing and debugging all of the boards...again...

Stay warm!

Those of you who read the Toronto Star may have notice that Singular Motion was featured on the front of the Wheels section yesterday! It's great to see that EV conversions are starting to get more publicity. There was certainly enough interest at the show to warrant such attention.

For those of you who missed it, check out the article online here: http://www.wheels.ca/newsFeatures/article/792247

Thanks Peter Gorrie for writing another great article.

Last weekend's EV Fest was a huge success! We stuffed every last component into the car, and even got most of the wiring done. We still had to use human-power to get the car into the showroom, but it looked very impressive. We had over 500 guests come by and check out the car, and they had some excellent questions. I'd like to send out a big thanks to the organizers for a job very well done. This was the first EV show in Toronto, and each year is going to get bigger and better.

Oh, and the 944 won the award for Best Techinal at the show. That's a pretty big honour for our not-quite-finished yet project. People are obviously seeing the car's final potential, which is great. EVs are supposed to functional, but the 944 goes one step further with it's flair. We're planning on adding a lot more character to this car over the winter, so stay tuned!

We might also be making an appearance in the Toronto Star, so keep an eye out for the EV Fest article coming out on Saturday October 23.

I tested the flywheel coupler again - this time with the taperlock bushing seated fully on the motor shaft, and the pull from the clutch slave cylinder pulled the coupler right off. We need some way of stopping any lateral translation of the hub whatsoever. My first thought was to add in a bolt to the end of the motor shaft which would clamp the coupler onto the shaft. This would work great, and a few other conversion I have seen are using this method. Unfortunately it won't work for us, because of the way that the hub is welded to the flywheel - there just isn't room for a bolt. To make this idea work, we'd have to start from scratch with a new flywheel, bushing, everything = $$$...

So I think we mave have some luck using a pin. We'll take the motor and coupler to our machinist, and hopefully he can drill a hole through the whole thing and put in a pin to hold everything in place. If that works - we'll be up and running in to time.

Plus tonight, I'll be bringing over all of the boards to Electrocraft to have all of the MOSFETs upgraded too. Graham will be coming to help out as well, so we should be able to get through the lot of them in no time.

I also started building the covers for the battery packs using clear acrylic plastic and aluminum edging. These covers will keep out water and foreign objects including stray wrenches and wandering fingers. We have come to appreciate just how powerful these batteries are.

At this rate, we might have enough time to spruce up the appearance of the 944 before EVFest too. It's still unlikely that we'll be able to drive it there, with all of the problems getting insurance. Still, being able to have a tour around the parking lot would be nice.

There have been a few very frustrating setbacks lately, involving the two most important systems: the battery and the motor coupling.

I'll start with the motor coupling. We had started off with a simple set screw coupler, but that introduced a fair amount of wobble with the single setting pin. Plus, the other half of the coupled that was welded to the flywheel was slightly mis-aligned, further increasing the wobble. We then had a machinist cut out the old hub and add in a new one for a taper-lock style coupler. He also made sure that the hub was centered and aligned properly before welding. This is a much better system, but it also changed the way the flywheel sat on the motor shaft. We were using a 1 1/2" spacer for the bell house adapter, and with this thickness, the taper-lock bushing would slide fully onto the shaft. We tried tightening it as much as possible to see if it would hold, but as soon as the clutch was depressed, the clutch/flywheel assembly slid down the shaft instead of releasing the pressure on the clutch disc. I have now removed a 1/2" of the spacer (luckily we're still using 1/4" plates of aluminum instead of a single solid milled piece) and the taper-lock sits fully on the shaft. I'm still worried that the assembly may slide on the shaft. One of the coupler kits online has a piece that threads into the end of the motor shaft and holds the bushing in place. With the 944 shaft though, it has a tip which needs to slide into a pilot bushing at the center of the flywheel - which now will slide right into the end of the motor shaft.... So there really isn't any room for a threaded bolt to hold the flywheel on. If the taper-lock isn't strong enough to prevent the flywheel from sliding, it'll be back to the drawing board, and probably a new flywheel. I'm not sure how many times it can be cut and welded without becoming weakened or warped.

Also, the BMS has been causing problems again. I thought that it was the resistors that we'd been having problems with before, but those checked out ok. Now, the mosfets that switch on/off the bypass resistors are burning up. We had made a few changes to the bypass resister values during our initial testing, and now the current going through these mosfets rose from about 1.5A to 4 or 5A. With the voltage drop across the mosfet, this is now about a Watt which the little switch needs to dissipate. It's designed to handle up to 12A, but not for sustained periods of time. Plus, they are located very close to the bypass resistors, which reach upwards of 80 degrees C under bypass! Yesterday Darius found a larger mosfet which had much better heat dissipation, and replaced a few of the old ones. We then did a test see just how hot these components were getting. The bypass resistors hit 75-80 degrees pretty quick. The new mosfets reached about 60, which is within their limits. The old mosfets however quickly got up to over 120 degrees C! No wonder they were burning out on several boards.

Clearly, the by-pass resistor design has its flaws. We'll replace the mosfets on all of the boards anyway so that I can start using the batteries, but Darius and I will start designing a new BMS starting next week. 

I'll be testing the flywheel coupler today, and hopefully I won't have to redesign that too.

Last week we were taking great strides towards completing the 944. The motor and clutch were installed with the new and improved flywheel/coupler. The batteries were installed and wired up. All of the accessories were mounted and wired as well. We had our first trial run using the full battery voltage and the controller. After a slight polarity issue from the key-switch, we had ignition (contact closure actually). With the drive wheels lifted off the ground, we spun up the motor - and had some seriously noisy shaking!

With our latest flywheel design, there was no way we should be getting vibrations like this. What seemed harmless at 12V was disasterous at 180V. So we had to remove the entire system to do root cause analysis.

To make a long story short - the clutch pressure plate had a broken spring! Our flywheel was spinning nice and true, as was the clutch/pressure plate. But, once the drive shaft was insterted into the system, the pressure plate's broken spring was unloading 1/3 of the clutch disc and essentially twisting the disc, transmitting a lot of movement into drive shaft/transmission and the rest of the car. At least it wasn't our flywheel design.

So yesterday I picked up a good-used pressure plate from Nineapart.com so we should be up and running again in no time.

While the batteries are back sitting in my living room again, it may be a good opportunity to take care of waterproofing the battery racks in case we get stuck driving through the rain at some point. We made a few structural modifications to the car during the last disassembly of the system so that we can now assemble the battery packs outside of the car and use the crane to drop in the whole pack all at once. This should save a lot of time if we ever have to remove the batteries again.

Two steps forward and one step back is our new motto.

In the previous post, I mentioned a slight vibration in the clutch assembly.... well, it quickly became apparent that we had to fix this vibration. There was a lot of testing, brainstorming, and trial solutions, but eventually we realized that there was no fix-it solution - we had to cut out the coupler and start again. The problem was in the weld between the shaft coupler and the flywheel. It turns out that the coupler wasn't completely flush and level with the flywheel when it was welded on. Now, considering that the welder knew that this was for a spinning application, I would have thought that he would at least have clamped the pieces together before welding. However, I'll take the blame as I never specifically asked for clamping and levelling. The result is a large "wobble" as the flywheel spins. The term is called runout. Often, the required runout tolerances are in the 0.1mm range or smaller, and we had a runout of 2mm! This, aided with poor tolerances of the shaft coupler on the shaft (very slight play prior to fitting the set screws) made for a very poorly spinning flywheel, and a ton of vibration. We're going to do it properly this time at a machine shop where they will make sure that everythink is centred, balanced and fitted precisely. During the brainstorming process we also came up with some ideas to improve other parts in the system, which we will be implementing as well. The parts are at the shop today and we may be able to do a trial run early next week. At least we're finally moving the right direction.

We also spent a lot of development time lately on the BMS for our LiFePO4 batteries. These batteries have a few unusual characteristics, and it has taken a while to learn their quirks. We have also made a numer of design changes to the BMS circuit boards to improve measurement capabilities and to handle real life charging scenarios better. We are still using a top-balancing system, which is certainly not ideal. However, we are not strictly enforcing the top voltage of each cell. The cells that reach the top first will slow down to let the others catch up, but only within about a 0.1V to 0.2V limit. This, along with a time limit in absorption mode should allow for some top-end imbalance in the cells. Couple this with regular (not sure how often yet) bottom balancing cycles, and we should have a robust system. We had to modify some component values in order to handle the extremely unbalanced state that we started with after we charged a few cells during board testing. The last change in resistor values will be completed early next week, and then we can started doing some actual charge/discharge cycles. This will allow us to test our new controller as well using the test facilities at Electrocraft.

In all, progress is slow, but we are fixing every problem as it arises, and learning valuable lessons as we go.

Well, it's been another long gap in the blog - but there has been lots of progress with the car. Yesterday, we finished installing the clutch and the engine mounts, and got the motor secured into the car. The battery system isn't ready yet, so we went for a test drive using the original 12V lead-acid battery! It was a low-speed excursion, but the acceleration up to 6kmph was really fast! There was some minor vibration in the flywheel, which we may need to remove at some point.

The BMS board have been built, and now the testing begins. Hopefully in a week or so they'll be ready, and the batteries can be fully charged for the first time.

Check out the video of our first drive in the SMEV944 in the Pictures section.